﻿// Spun AJAX Framework
// Copyright (C) 2008 Blake Hegerle
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using Formality.FormalSystem.Parser;

namespace Formality.FormalSystem
{
    public abstract class Sentence
    {
        public string Id { get; set; }
        public string DisplayId { get; set; }

        public abstract Inference? Implies(Proposition Goal, IEnumerable<Sentence> Given);

        public static Sentence Parse(string Input)
        {
            return SentenceParser.Instance.Parse(Input);
        }

        public static implicit operator Sentence(string Input)
        {
            return Sentence.Parse(Input);
        }

        public abstract bool Equals(Sentence obj);
        public abstract int HashCode { get; }
        public abstract void Serialize(TextWriter Writer, bool Detailed);
        public abstract void Bind(Bindings Bindings, int Depth);

        #region Object overrides
        public override bool Equals(object obj)
        {
            var that = obj as Sentence;

            return (that != null) ? this.Equals(that) : false;
        }

        public override int GetHashCode()
        {
            return HashCode;
        }

        public override string ToString()
        {
            var Writer = new StringWriter();
            Serialize(Writer, false);
            return Writer.ToString();
        }
        #endregion
    }
}
